I have a 560sel that is very hard to start when warm after sitting for a few minutes, the primary fuel pressure holds overnight, but I noticed that the fuel distributor was leaking fuel into the throttle body at rest so I replaced the fuel dist. with a rebuilt unit and it does the same thing, almost all the components have been replaced. Did I get a bad dist or could it be something else. The only way that the car will start warm is by holding the throttle to the floor while cranking for a long time (like it's flooded) and then when it starts it blows black smoke out the exhaust. any help will be appreciated.

On my 560sel the only place I see fuel leaking is from the bottom of the fuel distributer, as far as I can tell coming from around the pin that the throttle plate depresses. Is this acceptable or can anything other than a faulty fuel dist cause this, because I've had the same symptom with the original and the replacement unit. I have also replaced all the fuel injectors, buckets and seals. I've replaced the fuel pumps, accumulator, pressure regulator, temp sensor, and like I said it holds pressure overnight. thanks for any help.On my 560sel the only place I see fuel leaking is from the bottom of the fuel distributer, as far as I can tell coming from around the pin that the throttle plate depresses. Is this acceptable or can anything other than a faulty fuel dist cause this, because I've had the same symptom with the original and the replacement unit. I have also replaced all the fuel injectors, buckets and seals. I've replaced the fuel pumps, accumulator, pressure regulator, temp sensor, and like I said it holds pressure overnight. thanks for any help.

The pressure on the car is 48psi at rest and 92psi while running, which seems to be within specs. I'm hezitant to replace the fuel dist. again since I' ve done it twice.. I bought the dist at performance automotive at a fraction of the price I found anywhere else, if this is my problem I'd appreciate any feedback before I call them again. thanksThe pressure on the car is 48psi at rest and 92psi while running, which seems to be within specs. I'm hezitant to replace the fuel dist. again since I' ve done it twice.. I bought the dist at performance automotive at a fraction of the price I found anywhere else, if this is my problem I'd appreciate any feedback before I call them again. thanks

All of the injectors seals and buckets were just replaced, is fuel supposed to leak out of the bottom of the fuel dist? in approx 35 min all the fuel from accumulator is leaking into intake below flap. thanks for any helpAll of the injectors seals and buckets were just replaced, is fuel supposed to leak out of the bottom of the fuel dist? in approx 35 min all the fuel from accumulator is leaking into intake below flap. thanks for any help

The black smoke is a sign of running rich, so chances are your car is still leaking fuel into the throttle body and the startup is especially rich. The injector itself (at the throttle body) is a likely culprit - if the pintle is leaking, or the O-rings that seal the injector in its housing are cracked, worn, or split (which is likely -they're rubber and are on a hot metal engine), then it can allow fuel to leak down and cause the choking richness that your car is seeing at startup. I'd look into an injector and/or O-ring replacement to cure the problem.

thanks Jeremy Dellow ,my name is Ed. i was just surfing around when i came across your solution for , runs rich. my 86 Benz 560 SL has this same fault.thanks Jeremy Dellow ,my name is Ed. i was just surfing around when i came across your solution for , runs rich. my 86 Benz 560 SL has this same fault.

We have received a number of warranty claims with the complaint of internally leaking fuel distributors. After extensive bench and in-vehicle testing of these fuel distributors, we have found that most of these parts are not defective.

When testing a fuel distributor in a vehicle, the only way to confirm internal leakage is by performing the leak test as described in our service literature.

A possible indication of an internally leaking fuel distributor is when the Lambda "On - Off" ratio readings at idle vs. 2500 rpm (1) cannot be brought within 10% of each other by adjusting the idle mixture adjusting screw.

If performing a visual check, please keep in mind that when pressing down the airflow sensor plate the control plunger is lifted off the seal which prevents fuel from leaking. By doing so, some fuel is allowed to seep down the plunger to act as a "lubricant" between the plunger and the plunger barrel in order to keep the free movement of the plunger.

Whenever the airflow sensor plate is pushed down and the plunger is lifted off its seal, it is normal for a slight seepage of fuel to be visible down into the intake. If the plate is held down long enough, a small puddle can form (note: with the fuel pumps shut off, the max. 2 cc content of the fuel accumulator can be pushed out).

Refer to Service Microfiche job no. 07.3-120 for all testing procedures.

Note:All warranty returned fuel distributors will be closely monitored. Non-defective parts will be returned to the dealer and the dealer's warranty reimbursement account debited.

(1)With purge line disconnected and pluggedthis is a bulletin i found Fuel Distributor - Leakage ConfirmationNotes
91mercedes04REF. NO. MBNA 07.3/18
TO:
OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE:
September 1991
SUBJECT:
ALL MODELS WITH CIS-E FUEL DISTRIBUTOR LEAKAGE
We have received a number of warranty claims with the complaint of internally leaking fuel distributors. After extensive bench and in-vehicle testing of these fuel distributors, we have found that most of these parts are not defective.
When testing a fuel distributor in a vehicle, the only way to confirm internal leakage is by performing the leak test as described in our service literature.
A possible indication of an internally leaking fuel distributor is when the Lambda "On - Off" ratio readings at idle vs. 2500 rpm (1) cannot be brought within 10% of each other by adjusting the idle mixture adjusting screw.
If performing a visual check, please keep in mind that when pressing down the airflow sensor plate the control plunger is lifted off the seal which prevents fuel from leaking. By doing so, some fuel is allowed to seep down the plunger to act as a "lubricant" between the plunger and the plunger barrel in order to keep the free movement of the plunger.
Whenever the airflow sensor plate is pushed down and the plunger is lifted off its seal, it is normal for a slight seepage of fuel to be visible down into the intake. If the plate is held down long enough, a small puddle can form (note: with the fuel pumps shut off, the max. 2 cc content of the fuel accumulator can be pushed out).
Refer to Service Microfiche job no. 07.3-120 for all testing procedures.
Note:
All warranty returned fuel distributors will be closely monitored. Non-defective parts will be returned to the dealer and the dealer's warranty reimbursement account debited.
(1)
With purge line disconnected and pluggedthis is a bulletin i found

Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.

Related Questions:

indicates fuel leak back and fuel pressure drop
check filter installation for seal not sitting properly, loose fuel line fitting , pump installed correctly (flow wise ), filter installed correctly (flow wise)
air getting in to fuel lines
the thing you are looking for is indicated by the initial hard start but when started runs ok ( good fuel to the engine eventually) and then by the fact that if the engine is allowed to sit for a long period the problem returns meaning that the fuel pressure is not being held
could even be a problem fuel pressure regulator allowing the fuel to bypass ( no pressure =hard starting) then gets enough pressure to run ok but allows that pressure to drain off over time

I would start by checking fuel pressure via the schrader valve on the fuel line (near the rear of the intake manifold). The vortec engines needed considerably higher fuel pressure than most to start cold, and it is quite common for a weak fuel pump to cause a cold only no start condition with that engine. You should see around 50-60 psi with the key on / engine off for about 3 seconds. Also, if the pressure drops very quickly after a few seconds, the fuel pressure regulator could be to blame.

if it contines to run fine dont mess with however if it starts acting out again sound like possibly loss of fuel pressure have it check next with gauge on fuel system allow it to sit overnight and see what gauge reads in am BEFORE trying to start engine let me know if you need help

if still under warranty have dealer perform fuel rail residual pressure test.probably defect w/pressure regulator /check valve in fuel tank.fuel rail does not hold residual pressure so when you start after sitting for extended periods it takes time for pressure to build up and vehicle to start.

The request doesn't say what the problem is...takes extra time to start?

Sounds like fuel-related - injectors/fuel pump/fuel filter? Is there a strong fuel smell or black exhaust for a few seconds/minutes after starting it when it's sat overnight? If so, then you've got a leak causing excessive fuel...kind like 'flooding' the engine on old cars w/Carbs.

It could also be the temp. sensor. If it thinks the car is 'warm' it won't give the car enought fuel to start when cold.

you could have a couple differnet issues. cold start misfires, an intake air leak, poor compression with engine cold,or a fuel pressure issue with a leaking injector or fuel pressure is bleeding back due to a faulty pressure regulator. my recommendation is to buy a fuel pressure gauge and monitor pressure overnight. you could also pull the fuel rail and see if an injector is leaking at the same time. you can spray the intake system with a highly volitile liquid(with engine running) to see if idle speed changes to check for an air leak

Sounds like you may have a leaky injector which is both leaking fuel into one of the cylinders, and bleeding down any fuel rail pressure. Extra fuel makes it hard to start, loss of rail pressure takes a few seconds for fuel pump to build pressure back up.